The bone protrusion in the middle of the chest may exist as follows: 1. It may be a normal bony protrusion, which is most common among patients with thin subcutaneous fat and relatively thin. In the upper part of the sternum, there is a sternal angle where the sternal stalk and the sternal body meet, located where the second rib cartilage intersects, and an obvious raised angle can be seen forward and upward. At the lowermost part of the sternum, between the rib arches on both sides, there is the saber process. In some patients, the saber process is longer and more prominent if the patient is thin. 2, there may be a pheochondrium, often seen in patients with severe malnutrition leading to rickets and secondary thoracic deformity, this deformity is characterized by the anterior and posterior diameter of the thorax is greater than the left and right, the diameter at the same time the sternum has a forward protrusion. 3, there may be old injury caused by bony hyperplasia, for example, in the sternum has old fracture For example, if the sternum has an old fracture, there may be excessive scab growth at the fracture end, and then the bony swelling protruding from the skin surface will remain afterwards.